A hollow sphere of radius 0.25 m is rotating at 13 rad/s about an axis that passes through its center. The mass of the sphere is 3.8 kg. Assuming a constant net torque is applied to the sphere, how much work is required to bring the sphere to a stop?
A)1.0 J
B)3.8 J
C)13 J
D)25 J
E)38 J

Question

Quizplus · Accepted Answer

The work done to stop the sphere is equal to the change in its rotational kinetic energy. The rotational kinetic energy is given by $ KE = \frac{1}{2} I \omega^2 $, where $ I = \frac{2}{3} m r^2 $ for a hollow sphere. Substituting the values, $ I = \frac{2}{3} \times 3.8 \times (0.25)^2 $, and $ \omega = 13 $ rad/s, the work done is approximately 13 J.

A Hollow Sphere of Radius 0